Breathing mask having a cellulose heat and moisture exchanger formed therein

ABSTRACT

The invention relates to a breathing mask comprising a mask portion (1) covering the mouth and nose of the wearer and a heat exchanger portion (2) made of a material capable of recovering heat and fitted in the mask portion (1), inhalation and exhalation air being arranged to flow through the heat exchanger portion to recover heat and moisture contained in the exhalation air and to transfer it into the inhalation air. To achieve a simple, light structure having no disadvantageous environmental effects, the mask portion (1) and the heat exchanger portion (2) are made of the same material, preferably of a biodegradable material.

The invention relates to a breathing mask comprising a mask portioncovering the mouth and the nose of the wearer and a heat exchangerportion made of a material capable of recovering heat and fitted in themask portion, inhalation and exhalation air being arranged to flowthrough the heat exchanger portion to recover heat and moisturecontained in the exhalation air and to transfer them into the inhalationair.

BACKGROUND OF THE INVENTION

A person working at subzero temperatures under winter conditions orstaying outdoors under very cold conditions in general, e.g. in arcticareas, has to breath in great amounts of cold, dry air. This is not onlyunhealthy but also substantially increases the loss of heat of theperson as the body tends to warm up the inhalation air to thetemperature of the body and this amount of heat is removed from the bodywith the exhalation air. In addition, dry inhalation air has adisadvantageous effect on the normal moistness of the mucous membrane ofthe respiratory passages.

Various breathing masks are previously known which are intended for usewhen working at subzero temperatures, whereby the purpose of the mask isto enable the recovery of heat and moisture from the exhalation air andto transfer them into the inhalation air. Examples of such known masksare those disclosed in FI Patent Specifications 49241 and 52019 and FIPatent Application 895044.

In principle, the masks described in the abovementioned patent documentsoperate completely flawlessly, but their usability is not the bestpossible. One factor impairing their usability is their impracticaldesign, as the shape of the masks deviates substantially from the shapeof the wearer's face. As the mask protrudes strongly from the face, itsusability is substantially deteriorated. With some of these masks, afurther drawback is the great weight caused by the disadvantageous shapeof the heat exchanger portion, which in some cases requires the use of arather large mask portion.

The solution disclosed in FI Patent Application 895044 provides aconsiderable improvement over the solutions disclosed in theabove-mentioned Patent Specifications. The only major drawback of thesolution of FI Patent Application 895044 is that the cost of manufactureof the construction cannot be reduced to such an extent that it would beprofitable to sell the mask as a disposable product in connection with asports competition, for example. Another factor speaking againstdisposability is that the materials used in the manufacture of thisbreathing mask are not biodegradable, and so the disposability wouldcause environmental problems. The solutions described in FI PatentSpecifications 49241 and 52019 have the same drawback.

The object of the invention is to provide a breathing mask by means ofwhich the drawbacks of the prior art can be eliminated. This is achievedby means of a breathing mask of the invention, which is characterized inthat the mask portion and the heat exchanger portion are made of thesame material.

SUMMARY OF THE INVENTION

An advantage of the invention is mainly that it is simple and provides aconstruction such that it can be disposed of without causingenvironmental problems and nevertheless has all the advantages of theprevious masks. The protective capacity of the breathing mask accordingto the invention is fully comparable with that of the previoussolutions, in addition to which the mask according to the inventiondegrades biologically relatively rapidly, which eliminates theenvironmental problems often associated with disposable products.Moreover, the breathing mask according to the invention is advantageousin manufacturing costs, and so the price of the finished product can bekept sufficiently low. Still another advantage of the invention is thatthe heat surfaces are substantially parallel with the flow of air andthe flow openings are accurately defined. This is of vital importance inview of the flow resistance.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a breathing mask according to the invention when positionedupon the face of the wearer; and

FIG. 2 is a perspective view of the breathing mask according to theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The figures illustrate the principal features of the preferredembodiment of the invention. The reference numeral 1 indicates a maskportion covering the mouth and the nose of the wearer, and the referencenumeral 2 indicates a heat exchanger portion. The heat exchanger portion2 is fitted in the mask portion in such a way that the inhalation andexhalation air flows through it. At the exhalation stage, the heatexchanger portion 2 recovers heat and moisture from the exhalation airand transfers them into the inhalation air at the inhalation stage. InFIG. 1, the reference numeral 3 indicates bands by means of which themask is fixed upon the wearer's face.

According to the basic idea of the invention, the mask portion 1 and theheat exchanger portion 2 are made of the same material. It has proved tobe especially advantageous to make both the heat exchanger portion 2 andthe mask portion 1 of a biodegradable material. The biodegradablematerial may be e.g. wood fibre.

The heat exchanger portion 2 and the mask portion can be manufactured asseparate parts and combined into a whole shown in the figures. However,it has proved to be especially advantageous to manufacture the heatexchanger portion 2 and the mask portion 1 in a single step into anintegral and seamless structure.

The breathing mask according to the invention can be manufactured e.g.by a drainage technique, in which fibres are drained by means of waterinto a mould or casting model. Another alternative is a so-calledair-laying technique, in which air is sucked through a casting modelpositioned on a wire.

The above-mentioned mould or casting model can be formed of a bodyhaving crossing slits by means of which a cavity or duct structurecomprising several parallel ducts 4 can be formed of the wood fibrematerial. The ducts appear clearly from FIG. 1 in particular. Thecross-section of the ducts 4 may be e.g. rhombic or rhomboidal. Thelength of the ducts 4 should be in the order of 15 to 20 mm, and thewall thickness should be about 0.5 to 1 mm. The walls between the ducts4 need not be air-tight because more surface area is obtained in thisway.

The breathing mask according to the invention can be made ofshort-fibred high-yield hardwood cellulose, such as eucalyptus CTMPfibres. Another example is native aspen CTMP pulp. If the duct systemrequires handling strength to some extent, a small amount, e.g. about10% of spruce CTMP pulp can be added to the short-fibred pulp. When thefibre network has been formed around a cast mould or the like positionedon a wire, e.g. a starch solution can be applied through this veryporous fibre network, if required. In the air-laying technique, it ispossible to spray a starch aerosol into the air flow of the fibres,whereby the fibre network is stiffened to some extent already inconnection with the drainage.

The heat exchanger portion 2, that is, the duct system, and the maskportion have to be saturated due to the moisture contained in breathingair. The duct system and the mask portion can be saturated e.g. by anybiodegradable polymer.

As mentioned above, the length of the ducts 4 of the heat exchangerportion 2 should be about 15 to 20 mm to provide a sufficient heattransfer capacity. Ducts of such a length can be advantageouslypositioned as shown in FIG. 1, whereby the heat exchanger portion doesnot substantially protrude from the outer surface of the wearer's face.By suitably shaping the heat exchanger portion, a sufficient surfacearea is provided in the duct system to obtain the required heat transfercapacity. One aims at a large heat storing mass and, correspondingly, ata high surface area/mass ratio on account of the heat transfer rate. Themask portion 1 is made gas-tight, which ensures that all breathing airpasses through the heat exchanger portion 2.

The above embodiment is not intended to restrict the invention in anyway, but the invention can be modified as desired within the scope ofthe claims. Accordingly, it is obvious that the breathing mask accordingto the invention or its details need not necessarily be similar to thoseshown in the figures but other solutions are possible as well. The mask,for instance, need not necessarily be fastened in place by means ofbands; instead, the mask portion can be fastened to a hood or the like.The mask portion may also be integral with the hood, etc. The maskportion is, of course, such that it adapts to the shape of the wearer'sface. The mask portion is preferably such that it can be shaped by thewearer and that it remains in this shape. In addition to wood fibre,many other materials can be used in the manufacture of the breathingmask according to the invention. Such materials include a wood fibrematerial saturated by any polymer, such as a biodegradable polymer,starch, various plastic materials, that is, biodegradable and, ifrequired, also non-degradable plastics, etc.

I claim:
 1. A breathing mask comprising:a heat exchanger portion made ofa material capable of recovering heat, the heat exchanger portion beingarranged to receive exhalation air recover heat and moisture containedin the exhalation air, and transfer said heat and moisture to inhalationair; a mask portion surrounding the heat exchanger portion andconfigured to cover the mouth and the nose of the wearer, the maskportion being essentially impermeable to gas; and wherein the maskportion and the heat exchanger portion comprise a light weightbiodegradabe cellulose material that is saturated with a polymer tostiffen the cellulose material will resist moisture.
 2. A breathing maskaccording to claim 1, wherein: the heat exchange portion and the maskportion form an integral seamless structure made in a single step.
 3. Abreathing mask according to claim wherein: the material used in themanufacture is wood fibre.
 4. A breathing mask according to claim 4,wherein: the wood fibre material comprises a short-fibred fibrematerial.
 5. A breathing mask according to claim 1, wherein: thematerial used in the manufacture comprises a wood fibre materialsaturated with a biodegradable polymer.
 6. A breathing mask according toclaim 5, wherein the polymer comprises starch.
 7. A breathing maskaccording to claim 1, wherein: the material comprises plastic.
 8. Thebreathing mask of claim 1, wherein:the mask portion and the heatexchanger portion consist of the same material.
 9. A breathing mask,comprising:a mask portion; a heat exchanger portion having a pluralityof ducts, the heat exchanger portion being configured to receiveexhalation air, recover heat and moisture contained in the exhalationair, and transfer said heat and moisture to inhalation air, the ductshaving a length of at least 15 mm to facilitate heat exchange betweenthe ducts and the inhalation and exhalation air; and wherein the maskportion and the heat exchanger each comprise a lightweight biodegradablecellulose material saturated with a polymer to stiffen the cellulosematerial so that the cellulose material will resist moisture.
 10. Thebreathing mask of claim 9, wherein:the plurality of ducts have a lengthin the order of 15 to 20 mm.
 11. The breathing mask of claim 9,wherein:the plurality of ducts have a rhombic cross-sectional shape. 12.The breathing mask of claim 9, wherein:the plurality of ducts areparallel to one another.
 13. The breathing mask of claim 9, wherein:theplurality of ducts have a wall thickness between 0.5 and 1 mm.